1. Field of the Invention
This invention relates to a vibratory parts-feeder.
2. Description of the Prior Art
A vibratory part-feeding device in which parts or workpieces are transported on a spiral track formed in a feeder bowl by torsional vibration, is widely known. Generally, it is provided with any posture-regulating means for putting the feeding part into a predetermined posture. The parts are supplied one by one under the predetermined posture to the next process from the vibratory part-feeding-device. However, some kinds of parts or parts of some shapes are apt to jam at the posture-regulating means. When the parts are jammed, they cannot be fed to the downstream side. The part-jamming is detected by any detecting means. A jam-releasing means such as air-jetting means is actuated with the detecting output of the detecting means. The jammed parts are forcibly ejected to the inside of the feeder bowl.
For example, the manufacture for attaching the air-jetting means to the feeder bowl is required for the feeder bowl. Further in some cases, a through hole for passing the jetted air should be made in the side wall of the feeder bowl. A manufacturing operation for making the through hole is very troublesome. The part-jamming cannot be released in some manufacturing errors of the through hole which direction, for example, is somewhat deviated from the predetermined direction.
Recently, an elliptic vibratory part-feeding device was developed, in which the feeder bowl is vibrated in an elliptical manner. A locus of the vibrating point on the wall surface of the feeder bowl is elliptic in the elliptic vibratory part-feeding device. Generally, a feeding speed of an elliptic vibratory part-feeding device is higher than that of a usual vibratory part-feeding device in which a locus of the point on the wall surface of the feeder bowl is linear along the curved surface of the wall of the feeder bowl. The part-jamming is more apt to occur in the elliptic vibratory part-feeding device than in the usual vibratory part-feeding device.
The same assignee (Shinko Electric Co., Ltd.) previously developed the elliptical vibratory part-feeding device disclosed in the U.S. Pat. No. 5,042,643 in which the part-jamming means is arranged, and when part-jamming is detected by the means, the feeding direction of the parts is reversed by the change-over of the phase-difference forming means. The jamming can be released without special manufacture and at lower cost.
However, since the phase difference is constant, only two elliptical vibrations of constant longer and shorter axis can be obtained. Parts of some kinds are frequently jammed and so changes of directions have to frequently be effected.